A flow battery is a type of rechargeable battery where chemical energy is provided by two chemical components dissolved in liquids contained within the system and separated by a membrane. These liquids flow through the system and react electrochemically, allowing the system to be "recharged" by replacing the liquid stores or by mixing new chemical components back into the liquid streams.

How Flow Battery Works

In a flow battery, the chemical energy is stored in chemical components dissolved in liquids contained in external tanks. These liquids are pumped from the tanks through the cell stack where the electrochemical reactions occur. In the cell stack, the liquids are separated by a membrane (solid or liquid barrier) that allows only the flow of ions between the two sides but prevents the mixing of the liquid electrolytes. During the charging cycle, an electrical current is applied which causes a chemical reaction that stores energy chemically in the electrolytes. During discharging, the flow is reversed and the chemicals react, releasing electrons and providing electrical energy. The key advantage of the Flow Battery architecture is that the power and energy capacities are independently scalable by increasing the size of the electrolyte storage tanks or the number of cells.

Addressing issues like increasing energy densities, reducing material costs, improving membrane durability are active areas of R&D. Standardization of designs, manufacturing processes and supply chains are other challenges that need to be overcome before flow batteries can realize their full potential at widespread commercial and grid scales. With increasing investments and technological advancements, flow batteries are expected to play a major role in enabling a renewable-based electricity grid in the coming decades.

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